1. Field of the Invention
This invention relates to connectors for electrically connecting a pin array circuit module and printed circuit board and the like, and electrical circuit packages for such components.
2. Description of the Prior Art
Connectors for connecting pin array circuit modules and printed circuit boards, and circuit package assemblies for such interconnected components, are well known in the art.
For example, in U.S. Pat. No. 4,059,323, "Apparatus For Interconnecting Plural Mating Members", R. Babuka et al, and assigned to the common assignee herein, there is disclosed a circuit package in which the input/output (I/O) pins of an integrated circuit module of the area array pin type are plugged into mating female members that are mounted in a corresponding array to a printed circuit board. The female members are metal connectors of the bifurcated spring type.
A description of one such type of bifurcated female connector is contained in U.S. Pat. No. 3,915,537, "Universal Electrical Connector", J. B. Harris et al, and assigned to the common assignee herein. It has a U-shaped configuration, the arms of which extend upwardly from a common main body portion. The contact surfaces are located on the inward faces of the resilient arms. The female connector has a stem, the upper end of which depends from the main common body portion. Part of the lower end of the stem is mounted to the board. When the connectors are mounted in an array to the board by their stems, the main body portion, resilient arms and contact surfaces of each connector are in an upright position and are extended at a uniform height above the surface of the printed circuit board. The connectors in the array are mounted to the board with the same identical orientation. In a manner well known to those skilled in the art, the female connector is mounted to the board by locating the lower end of the stem portion of the connector in and bonding it to one of the plated through holes (PTHs) of the printed circuit board, which holes are arranged in an array corresponding to the pin array of the module. Each such plated through hole is connected to preselected one or more circuit layers of the board. As a result, when the pin of the module is plugged into its mating female connector, the pin will be connected to the circuitry of the board to which the particular female connector is connected, thus connecting the circuitry of the module that is connected to the pin to the particular one or more circuit layers of the board.
Affixed to the printed circuit board of the aforementioned U.S. Pat. No. 4,059,323 is a base carrier insulator member. It has an array of recesses opening corresponding to the array of of female connectors mounted to the board and hence to the array of the module pins. Each recess has two pockets in an open and facing adjoining relationship. The first pocket encompasses and houses the two resilient arms and associated contact surfaces of one of the bifurcated spring female members mounted in the board that pass into the recesses from one side of the base carrier insulator member. The second pocket is laterally offset from and opens into the first pocket as aforementioned. The module pins are initially inserted from the opposite side of the base member into their corresponding respective second pockets, and then with the assistance of a cam actuator means, the pins are moved in the lateral direction out of the second pockets and into the first pockets towards the opening formed in the spacing between the two arms of the female connector associated with the particular pin. When the pin engages the leading edges of the two arms, the motion of the pin continues. As a result, the pin pushes against the leading edges causing the stem to deflect, i.e. pivot, in the direction of pin movement. The pivoting occurs about an upper part of the stem that protrudes outwardly from the PTH in which it is mounted. The stem, and thus the two arms it carries, is pivotally deflected from the normal upright position of the protruding stem part. The deflection of the stem is stopped when the common body portion between the two arms of the connector is obstructed by the wall of the first pocket. The pin continues to travel in the same direction causing the pin to deflect the two arms of the connector away from each other in a direction transverse to the direction of the pin movement. As the pin continues to move in the same direction, it enters the space therebetween and slides between the two contact surfaces in a contact wiping and captivated action manner. The cam actuator next is adapted to then reverse the direction of the pin. As a result, the now captivated pin carries the female connector, and hence the protruding part of the stem moves from its deflected position back to its former upright position thus removing the stress in the stem. As such, the pin is now properly engaged with the female connector.
More detailed information about the aforedescribed type of electrical connector apparatus for connecting a pin array circuit module to a printed circuit board and electronic packaging apparatus incorporating the same may be found in the aforementioned patents and other references such as, for example, in the following articles: "Thermal Conduction Module: A High Performance Multilayer Ceramic Substrate" A. J. Blodgett et al, and "A New Set of Printed-Circuit Technologies for the IBM 3081 Processor Unit", D. P. Seraphim, IBM J. RES. DEVELOP, Vol. 26, No. 1, Jan. 1982, pp 30-36 and 37-44, respectively.
U.S. Pat. No. 4,076,357, "Laminated Programmable Microstrip Interconnector", A. B. Cistola, and assigned to the common assignee herein, is another example of a connector that interconnects a pin array module to a circuit board. The connector has laminated printed circuit subtrates which have wrap around conductive lands formed on their respective aligned common bottom edges. The commonly aligned laminations are mounted along their respective common bottom edges normal to the plane of the circuit board. The lands are soldered bonded to the aligned contact pads on the outer planar surface of the printed circuit board. Recesses which are inwardly formed from the opposite, i.e. top, common edges of the laminations house individual bifurcated metal spring connectors which mate with the pins of the module. Each bifurcated connector has a stem which is affixed, e.g. by a solder bond, to a printed circuit conductor on the particular lamination that is integrally connected with one of the lands located along the bottom edge of the lamination.
It is also known in the connector prior art to provide an electrical conductive layer on a plastic body, for example, cf. U.S. Pat. Nos. 3,363,221, 3,638,166 and 4,662,702 and the article entitled "Shielded Connector Assembly Using Metalized Plastic", IBM Technical Disclosure Bulletin, Vol. 30, No. 12, May 1988, pp 84-85.
Thus, in U.S. Pat. No. 3,363,221, co-axial and shielded cable connectors are made as plated plastic electrical connectors. More particularly, the connector is made with mating plug and jack connector halves that have electrically conductive plating on their respective plastic shell bodies.
In U.S. Pat. No. 3,638,166 a pin socket connector is configured as a U-shape plastic body that has a conductive layer on the the inwardly facing walls of the two legs of its U shape. A discrete wire conductor passes through a bore in the bottom of the plastic body and is connected to the conductive layer. Multiple sockets may be commonly ganged by being integrally formed from a common plastic bar, each socket having its own wire connector. The mating pin is held between two inwardly facing plated bulges formed at the free ends of the two plated resilient formed legs of the socket. The conductive layer is formed by electrolysis, by deposition of an electrically conductive lacquer or emulsion, by vapor depositing, or by forcing or pressing a metallic strip against the inwardly facing walls of the U shaped socket.
In U.S. Pat. No. 4,662,702, an electrical spring contact for a connector is essentially comprised of: a first metal layer of a desired conductivity selected from the group of copper, silver, gold, aluminum and the like and alloys of these metals, which first metal layer forms the contact element of the contact; a second metal layer having a required springiness selected from the group iron alloys as spring stainless steel, copper alloys as spring beryllium-copper alloy, a metal containing spring reinforcing agent such as whisker and the like, amorphous metal and the like, and may be preferably selected from iron, cobalt, titanium, zirconium and nickel base alloys, which second layer provides the spring characteristics for the contact; and a plastic layer interposed between the two metal layers for their support. The plastic material is selected from epoxy, polyester, polyimide, polyamide or polyolefin resin and the like and may preferably be selected from the group of phenol, amino, epoxide, furan, polyether, ally, polyimide, polyamide, polyester, polycarbonic ester, polyphenylene sulfide, polyolefin, vinyl and silicone resins. The metal layers may be affixed to the plastic layer by an adhesive bond, or by means of electroplating, vapor deposition or spattering or ion planting.
In the aforementioned IBM Technical Disclosure Bulletin article, the plastic housings of an electrical connector assembly are metalized to reduce connector cross-track noise in a high speed, impedance-controlled digital transmission system.
The aforedescribed prior art connectors and circuit packages, while found to be generally satisfactory for certain high density applications, are not readily amenable for present higher density applications, i.e. higher density circuits and/or higher density pin arrays, e.g. arrays with 2000 or more pins. Moreover, the prior art devices have configurations which are complex and/or have a relative high number of moving parts and/or are susceptibility to deformation during their formation, assembly or disassembly and/or mating. The prior art devices, in addition, are not amenable to miniaturization or precision alignment between mating members and hence adversely effect the reliability required for such higher density applications.